(a) Field of the Invention
This invention relates to 4-(3,4-diaminophenyl)pyridine, useful as cardiotonic agent, and to its preparation.
(b) Description of the Prior Art
3-(3,4-Diaminophenyl)pyridine was prepared by Coates et al, J. Chem. Soc. 1943, 406 (413), by catalytic hydrogenation of the corresponding 3-(4-amino-3-nitrophenyl)pyridine using platinum oxide as catalyst. 3-(3,4-Diaminophenyl)pyridine was used as an intermediate to prepare 6-.beta.-(pyridinyl)-quinoxalines.
2-(3,4-Diaminophenyl)pyridine was prepared by Cook et al., J. Chem. Soc. 1943, 404 (405), by reduction of 2-(4-amino-3-nitrophenyl)pyridine with stannous chloride and hydrochloric acid in ethanol. 2-(3,4-Diaminophenyl)pyridine was used as an intermediate to prepare 6-.alpha.-(pyridinyl)quinoxalines.
4-(4-Acetylamino-3-nitrophenyl)pyridine and 4-(4-amino-3-nitrophenyl)pyridine are disclosed as intermediates in an multi-step synthesis of 4-(3-nitrophenyl)pyridine in the Carabateas and Brundage U.S. Pat. No. 3,994,903, issued Nov. 30, 1976.